In the semiconductor industry as well as in other industries, there is need for "united" or combined flow regimes in a single modular chemical delivery substrate block. For example, as shown in FIGS. 1A, 2A, 3A and 4A, some designs for modular chemical delivery blocks (4,8) have typically achieved process chemical flows for both directional flow along line (6) (south to north, or north to south when viewed from the top) and transverse flow along line (14) (cast to west, or west to east when viewed from the top) by combining a top layer block (4) to provide directional process flow (6) with a bottom layer block (8) to provide a transverse directional process flow (14). As shown in FIGS. 1A and 2A, this is typically accomplished by using fasteners (12) (usually threaded bolts and/or nuts) to attach the multiple layer blocks (4,8) together. Although this prior art multi-block multi-layer approach satisfies the requirement for having both directional and transverse process (and/or purge) chemical flows, several limitations to utilizing modular chemical delivery substrates result.
First, in a multi-block multi-layer design, the center height (18) measured from the top of the process stream line (20) to the bottom of the block assembly (24) is effectively much higher than that in a design using a single block (28) of the present invention as shown in FIG. 1B which can provide the same chemical flow regimes. Because each chemical flow direction is achieved with two or more individual blocks (4,8) for multi-layer substrate block assemblies, the typical total stacking height (32) of 1.054" (26.8 mm) increases linearly in proportion to the substrate thicknesses of each block in a dual stack design. This contributes to both excessive system weight and the total height of the resulting system. Secondly, when compared to a single block design, prior art multi-block multi-layer modular chemical delivery systems on average have a higher mass of material (usually machined or cast from stainless steel) and thus tend to be heavy and bulky in a completed modular system assembly. For many applications, excess system size and weight present extreme disadvantages for the user who wishes to use traditional modular chemical substrate delivery systems.
Multi-layer blocks that are stacked together via a fastened interface also require at least one additional seal (36) per layer and additional fasteners (40) in order to provide a leak-proof system for potentially corrosive or hazardous chemical transport through the system. Although prior art multi-layer block designs provide directional and transverse chemical flow regimes, the additional joining fasteners (40) and seals (36) required also increases total costs. Therefore, modular chemical delivery blocks which can provide both directional and transverse chemical flows independently and which are integrated into a single substrate block design with united flows are desired and needed.
Furthermore, as shown in FIGS. 3A and 3B, multi-layer stacked blocks having multi-directional flow capabilities increase the total chemical wetted volume of the bore (52) inside each substrate assembly system as compared to the bore (53) in the unified design of the present invention. This increase can reduce the dry down times when an inert gas carrier is used to dry out the moisture content of the chemical system. Per the industry standard SEMI 2787.1, the internal diameter of both bores (52,53) must be a minimum of 0.18" (4.57 mm). Thus the volume (V) of wetted area V=A.times.L (where A=IID.sup.2 /4 and L=length of wetted bore) increases with the stacking heights and corresponding increase in the length of the bore. In FIG. 3A, the length L of the bore (54) for a multi-layer assembly is almost twice that of the unified single layer block bore length (55) shown in FIG. 3B. Clearly, a method and system for providing multiple flow regimes (directional and/or transverse flow) in a single, united chemical distribution block overcomes many disadvantages of the prior art. Additionally, certain mechanical features and constraints specific to this design are presented for achieving such a multidirectional flow in a unified block substrate.